The 40-year-old actor revealed he knew the 29-year-old actress was The One during a romantic date in New York while recalling the moment he fell for Lively in the December issue of GQ.
"We were hanging out at this little restaurant in Tribeca that's open really late, and this song came on and I was just like, 'Want to dance?' No one was in the there, so it was just totally empty," Reynolds said.
"It was just one of those moments where halfway through the dance, it was like, 'Oh, I think I just crossed a line.' And then I walked her home. And uh, you know, I don't really need to go into what happened after that," he joked.
Reynolds and Lively met on the set of Green Lantern in 2010 and married in Mount Pleasant, S.C., in 2012. The couple revisited another favorite restaurant for the actor's 40th birthday in October.
"@_o_ya_ We fell in love at your restaurant in Boston. We stay in love at your restaurant in NY. Thank you for the BEST food and memories! You are our favorite!! Another happy birthday with @vancityreynolds. Hey, Reynolds, I like you a whole lot. Just sayin'..." Lively wrote on Instagram.
Reynolds and Lively welcomed daughter James in 2014, and have yet to reveal the name of their second daughter, who was born in September. The Deadpool star admitted on an episode of Conan this month that parenting "two under two is tough."